Measuring temperature rise during orthopaedic surgical procedures

• 24 tests on bovine bone using 3 types of orthopaedic surgical screw procedures.
• Compared techniques for measuring bone temperature.
• Results indicate relative performance of surgical procedures.
• Results show new method of measuring temperature compared to existing methods.

A reliable means for measuring temperatures generated during surgical procedures is needed to recommend best practices for inserting fixation devices and minimizing the risk of osteonecrosis. Twenty four screw tests for three surgical procedures were conducted using the four thermocouples in the bone and one thermocouple in the screw. The maximum temperature rise recorded from the thermocouple in the screw (92.7 ± 8.9 °C, 158.7 ± 20.9 °C, 204.4 ± 35.2 °C) was consistently higher than the average temperature rise recorded in the bone (31.8 ± 9.3 °C, 44.9 ± 12.4 °C, 77.3 ± 12.7 °C). The same overall trend between the temperatures that resulted from three screw insertion procedures was recorded with significant statistical analyses using either the thermocouple in the screw or the average of several in-bone thermocouples. Placing a single thermocouple in the bone was determined to have limitations in accurately comparing temperatures from different external fixation screw insertion procedures. Using the preferred measurement techniques, a standard screw with a predrilled hole was found to have the lowest maximum temperatures for the shortest duration compared to the other two insertion procedures. Future studies evaluating bone temperature increase need to use reliable temperature measurements for recommending best practices to surgeons.